The present disclosure relates to a solid-state imaging element having a multilayer structure including a photoelectric conversion unit and a wiring layer, a method for producing the solid-state imaging element, and an electronic device including the solid-state imaging element.
In a solid-state imaging element in which a plurality of photoelectric conversion units are arranged, proposed structures for successfully improving the optical sensitivity and achieving a higher pixel density include, for example, a back-illuminated structure. In a back-illuminated solid-state imaging element, the photoelectric conversion units are provided in the back surface of a semiconductor substrate, the back surface being opposite to the front surface on which circuitry, wiring, and the like are provided, and thus incident light is received by the photoelectric conversion units through the back surface. Sensitivity can be improved in such a back-illuminated solid-state imaging element, because the circuitry, wiring, and the like, which block or reflect incident light, are not provided on the light-receiving side of the element (for example, see Japanese Unexamined Patent Application Publication No. 2008-182142).
Further, in the above-described back-illuminated solid-state imaging element, it has been proposed to provide a control gate electrode on a surface opposite to the light-receiving surface in the photoelectric conversion units, and to apply voltage to the photoelectric conversion units to control potential and efficiently transfer signal charges (for example, see Japanese Unexamined Patent Application Publication No. 2007-258684).